U.S. patent application number 10/913668 was filed with the patent office on 2005-03-17 for gas sampling bag.
This patent application is currently assigned to Horiba, Ltd.. Invention is credited to Hirai, Hitoshi, Katumata, Hiroaki, Mizutaka, Toshio, Ohashi, Hideki, Uchida, Kenichi, Yoda, Kimikazu.
Application Number | 20050056103 10/913668 |
Document ID | / |
Family ID | 34213280 |
Filed Date | 2005-03-17 |
United States Patent
Application |
20050056103 |
Kind Code |
A1 |
Hirai, Hitoshi ; et
al. |
March 17, 2005 |
Gas sampling bag
Abstract
A gas sampling bag is capable of blowing out the gas uniformly
into the bag main body, and filling the bag main body with gas in a
securely mixed state. A gas sampling bag that is connected to a
constant volume sampling passage, contains a pipe, on which a
plurality of gas inlet/outlet holes are formed, in a bag main body,
and allows the gas to flow into/out of the bag main body through
the gas inlet/outlet holes. The opening of the plurality of gas
inlet/outlet holes is formed in such a manner that the size is
minimized while the pressure loss is suppressed so as not to
increase as far as possible.
Inventors: |
Hirai, Hitoshi; (Kyoto,
JP) ; Ohashi, Hideki; (Kyoto, JP) ; Mizutaka,
Toshio; (Kyoto, JP) ; Yoda, Kimikazu;
(Susono-shi, JP) ; Uchida, Kenichi; (Susono-shi,
JP) ; Katumata, Hiroaki; (Susono-shi, JP) |
Correspondence
Address: |
BROOKS KUSHMAN P.C.
1000 TOWN CENTER
TWENTY-SECOND FLOOR
SOUTHFIELD
MI
48075
US
|
Assignee: |
Horiba, Ltd.
Minami-ku
JP
|
Family ID: |
34213280 |
Appl. No.: |
10/913668 |
Filed: |
August 6, 2004 |
Current U.S.
Class: |
73/864.51 ;
73/863.81; 73/864.62 |
Current CPC
Class: |
G01N 1/2252 20130101;
G01N 2001/2264 20130101 |
Class at
Publication: |
073/864.51 ;
073/863.81; 073/864.62 |
International
Class: |
G01N 001/22; G01N
001/24 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 6, 2003 |
JP |
2003-287385 |
Claims
What is claimed is:
1. A gas sampling bag for connecting to a constant volume sampling
passage, the gas sampling bag comprising: a bag main body; and a
pipe, in the bag main body, on which a plurality of gas
inlet/outlet holes are formed to allow the gas to flow into/out of
the bag main body through the gas inlet/outlet holes, wherein the
openings for the plurality of gas inlet/outlet holes are formed in
such a manner with reduced size so that pressure loss is suppressed
to blow out the gas generally uniformly from all gas inlet/outlet
holes opened in the pipe and flow the gas into the bag main
body.
2. The gas sampling bag of claim 1 wherein the opening size of the
gas inlet/outlet holes is set so that the total area of the
plurality of gas inlet/outlet holes formed in the pipe is almost
equal to an opening sectional area of the pipe.
3. The gas sampling bag of claim 1 wherein the opening size of the
gas inlet/outlet holes is set so that the total area of the
plurality of gas inlet/outlet holes formed in the pipe is less than
an opening sectional area of the pipe.
4. The gas sampling bag of claim 1 wherein the bag main body is
formed of fluoroplastic sheets.
5. The gas sampling bag of claim 1 wherein the plurality of
inlet/outlet holes is composed of holes having generally the same
size.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a gas sampling bag and,
more particularly, to a gas sampling bag that is connected to a
constant volume sampling passage, contains a pipe, on which a
plurality of gas inlet/outlet holes are formed, in a bag main body,
and allows gas to flow into/out of the bag main body through the
gas inlet/outlet holes.
[0003] 2. Background Art
[0004] One of the sampling methods of emission gas exhausted from
an automobile engine or the like is, for example, the constant
volume sampling (CVS) method. In this CVS method, the emission gas
having transiently changing flow rate is diluted with the air, and
the flow rate of the diluted gas is defined as known flow rate, and
the weight of components is calculated by using the diluted gas
component concentration and the known flow rate.
[0005] In one of the measuring techniques of gas concentration of
the CVS method, the sampled diluted gas is put in a gas sampling
bag, and the gas in this gas sampling bag is supplied into a gas
analyzer.
[0006] FIG. 5 schematically shows a conventional example of this
gas sampling bag. In FIG. 5, reference numeral 51 denotes a gas
sampling bag, and reference numeral 52 denotes a bag main body
stretchably formed by gluing, for example, fluoroplastic sheets.
Reference numeral 53 is a pipe made of, for example, fluoroplastic
material of a circular cross-section provided inside the bag main
body 52, and it is formed like a shape of 8 in plan view. In the
middle of the pipe 53, a gas junction 54 is formed as a junction to
an external gas passage, and a plurality of gas inlet/outlet holes
55 of proper small diameter are formed at uniform intervals on the
periphery of the overall length of the pipe 53.
[0007] In the gas sampling bag 51 having such a configuration, the
gas junction 54 is connected to the constant volume sampling
passage through a valve and, by opening the valve, the gas from the
constant volume sampling passage is introduced into the pipe 53
through the gas junction 54 and flows into the bag main body 52
through the plurality of gas inlet/outlet holes 55. In the bag main
body 52, the gas is mixed securely, and a gas of uniform
concentration is prepared. The gas sampling bag 51 is connected to
a gas supply path to a gas analyzer through a valve and, by opening
the valve, the gas in the bag main body 52 flows into the gas
junction 54 through the plurality of gas inlet/outlet holes 55 and
pipe 53 and flows out in the gas supply direction.
[0008] In the conventional gas sampling bag 51, however, in order
to decrease the pressure loss of the gas when passing the gas
inlet/outlet holes 55 as much as possible, when the inner diameter
of the pipe 53 is, for example, 6 mm, this pipe 53 has 52 gas
inlet/outlet holes 55 each having an opening diameter of, for
example, 3 mm. In the gas sampling bag 51 formed in this manner, if
the concentration changes significantly in the constant volume
sampling passage, gas mixing in the bag main body 52 is not always
sufficient, and the gas concentration in the bag main body 52 is
not always uniform.
[0009] To avoid uneven gas concentration in the bag main body 52 of
the gas sampling bag 51, the gas filling rate in the bag main body
52 may be raised, the gas injection time in the bag main body 52
may be extended, or the gas flowing rate into the bag main body 52
may be increased. However, in the gas sampling bag 51 connected to
the constant volume sampling passage, the overall capacity of the
bag main body 52 is limited, and cannot be increased simply in
relation to the test mode duration and injection flow rate.
[0010] Under such restrictions, the present inventors investigated
and discovered as follows: in the conventional gas sampling bag 51,
it was attempted to minimize pressure loss of gas when passing the
gas inlet/outlet holes, and all gas flowing into the pipe 53
through the gas junction 54 does not flow into the bag main body 52
through all of gas inlet/outlet holes 55, but flows into the bag
main body 52 through a limited number of gas inlet/outlet holes 55
in the vicinity of the gas junction 54; therefore, there is a high
possibility in that the gas was not mixed sufficiently.
SUMMARY OF THE INVENTION
[0011] It is therefore an object of the invention to present a gas
sampling bag capable of blowing out the gas uniformly into the bag
main body, and filling the bag main body with gas in a securely
mixed state.
[0012] To achieve the object, the invention provides a gas sampling
bag that is connected to a constant volume sampling passage,
contains a pipe, on which a plurality of gas inlet/outlet holes are
formed, in a bag main body, and allows the gas to flow into/out of
the bag main body through the gas inlet/outlet holes, in which the
opening of the plurality of gas inlet/outlet holes is formed in
such a manner that the size is minimized while the pressure loss is
suppressed so as not to increase as far as possible.
[0013] More specifically, it is comprehended that the opening size
of the gas inlet/outlet holes is set so that the total area of the
plurality of gas inlet/outlet holes formed in the pipe may be
almost equal to or smaller than the opening sectional area of the
pipe.
[0014] At the more detailed level, it is further comprehended that
in the gas sampling bag having such a configuration, since the size
of the opening of the plurality of gas inlet/outlet holes formed in
the pipe contained in the bag main body is determined so that the
pressure loss may be suppressed to be minimum so as not to increase
as far as possible, the pressure in all the gas inlet/outlet holes
is generally higher than in the conventional gas sampling bag;
hence, the flow rate of the gas blown out from the gas inlet/outlet
holes into the bag main body is higher. As a result, not limited to
the plural gas inlet/outlet holes in the vicinity of the gas
junction, the gas is blown out almost uniformly from all gas
inlet/outlet holes opened in the pipe, and flows into the bag main
body.
[0015] Therefore, in the gas sampling bag of the invention, the gas
sampled in the bag main body is securely mixed and is contained;
hence, a mixed gas of uniform concentration can be supplied as
sample gas to the gas analyzer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a diagram schematically showing an example of an
automobile emission measuring apparatus in which a gas sampling bag
of the invention is assembled;
[0017] FIG. 2 is a diagram showing an example of the gas sampling
bag;
[0018] FIG. 3 is a partially enlarged view showing an open state of
gas inlet/outlet holes in the gas sampling bag;
[0019] FIG. 4 is a diagram showing a relation between an opening
diameter of gas inlet/outlet holes in the pipe and a mixing error;
and
[0020] FIG. 5 is a diagram showing a conventional gas sampling
bag.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] FIGS. 1 to 4 show a preferred embodiment of the invention.
FIG. 1 is a diagram schematically showing an example of an
automobile emission measuring apparatus in which a gas sampling bag
of the invention is assembled. In FIG. 1, reference numeral 1
denotes a sample gas diluting pipe, and emission gas G exhausted
from an automobile engine as an emission source flows in from its
upstream side. Reference numeral 2 denotes a diluting air
introduction pipe connected to the sample gas diluting pipe 1, and
diluting air A is introduced into the sample gas diluting pipe 1
through a filter 3. Reference numeral 4 denotes a venturi tube
connected to the downstream side of the sample gas diluting pipe 1,
and reference numeral 5 denotes a blower as a suction device
provided in a duct 6 at the downstream side of this venturi tube 4,
and emission gas diluted by the air A (hereinafter, referred to as
"diluted emission gas") G.sub.1 is sucked in at a specified flow
rate Q.sub.1 by the blower 5.
[0022] Reference numeral 7 is a constant volume sampling passage
for sampling the diluted emission gas G.sub.1 flowing through the
sample gas diluting pipe 1 at a constant volume, and its highest
upstream part has a gas sampling unit 8 composed of a venturi tube
having the function similar to that of the venturi tube 4, while a
suction pump 9 is provided at the downstream side, and a plurality
of gas sampling bags (the structure thereof will be described
later) 10 are provided in a downstream side passage 7a. That is, in
the passage 7a, a plurality of branch passages 11 are connected,
and a gas sampling bag 10 is connected to each branch passage 11
through an opening valve 12. Each gas sampling bag 10 is connected
to a gas passage 14 having an opening valve 13, and the downstream
side of these gas passages 14 is connected to a gas supply path 16
to a gas analyzer 15. Reference numeral 17 is a suction pump
provided in the gas supply path 16.
[0023] In the constant volume sampling passage 7, supposing the
flow rate when sucking the diluted emission gas G.sub.1 by the gas
sampling unit 8 to be Q.sub.2, the suction pump 9 is operated so
that Q.sub.2/Q.sub.1 may be always constant. More specifically,
when filling one gas sampling bag 10 with the diluted emission gas
G.sub.1, the opening valve 13 provided in the gas passage 14
corresponding to this gas sampling bag 10 is closed, while the
opening valve 12 provided in the branch passage 11 is opened, and
the gas sampling bag 10 is filled with the diluted emission gas
G.sub.1 which is sampled in the constant ratio Q.sub.2/Q.sub.1. In
the case of analyzing the diluted emission gas G.sub.1 in the gas
sampling bag 10, the opening valve 12 is closed and the opening
valve 13 provided in the gas passage 14 is opened, so that the
diluted emission gas G.sub.1 is supplied as sample gas into the gas
analyzer 15 through the gas supply path 16.
[0024] The gas sampling bag 10 is composed as shown in FIGS. 2 and
3, in which a bag main body 18 stretchably formed by gluing, for
example, fluoroplastic sheets, and a pipe 19 made of, for example,
fluoroplastic material of a circular cross-section is provided in
its inside, for example, like a shape of 8 in plan view. In the
middle of the pipe 19, a gas junction 20 is formed to be connected
to the outside gas passages (in this example, passages 11, 14), and
a plurality (52 in this example) of gas inlet/outlet holes 21 of
proper small diameter are formed at uniform intervals on the
periphery of the overall length of the pipe 19. The gas
inlet/outlet holes 21 are opened so as not to be blocked by main
body members 18a, 18g for forming the bag main body 18 as shown in
FIG. 3, and more preferably are formed oppositely to the direction
of diameter of the pipe 19.
[0025] The gas inlet/outlet holes 21 are opened so as to suppress
and minimize the pressure loss so as not to increased as far as
possible. More specifically, supposing the opening sectional area
of the pipe 19 to be S.sub.19 and the total opening area of the gas
inlet/outlet holes 21 to be S.sub.21, it is defined to satisfy the
relation of S.sub.19.gtoreq.S.sub.21, more preferably
S.sub.19>S.sub.21.
[0026] More strictly, in order that the total opening area S.sub.21
of the gas inlet/outlet holes 21 may be smaller than the opening
sectional area S.sub.19 of the pipe 19, the opening diameter of the
gas inlet/outlet holes 21 is decreased, but the pressure loss due
to reduction of diameter is set as small as possible, and extreme
delay in injection and exhaust is avoided.
[0027] In the gas sampling bag 10 thus configured, since the size
of the opening of the gas inlet/outlet holes 21 formed in the pipe
19 provided in the bag main body 18 is minimized so as to suppress
the pressure loss so as not to increase as far as possible, the
pressure in all of the gas inlet/outlet holes 21 is higher than in
the conventional gas sampling bag; hence, the flow rate of the gas
blown out from the gas inlet/outlet holes 21 into the bag main body
19 is increased. As a result, not limited to the plural gas
inlet/outlet holes 21 in the vicinity of the gas junction 20, the
gas is blown out almost uniformly from all gas inlet/outlet holes
21 opened in the pipe 19, and flows into the bag main body 18.
Therefore, in the gas sampling bag 10, the gas is securely mixed
and contained in the bag main body 18; hence, mixed gas of uniform
concentration can be supplied as sample gas to the gas analyzer
15.
[0028] FIG. 4 shows mixing errors (mixing effects) of gas in the
gas sampling bag 10 when tested in the following conditions, by
setting the opening diameter of the gas inlet/outlet holes 21
formed in the pipe 19 contained in the gas sampling bag 10 in three
different sizes, 3 mm, 1.5 mm and 0.5 mm. In the figure, the square
mark indicates the data when filling the gas sampling bag 10 at gas
flow rate of 6 L/min, and the circle mark indicates the data at
flow rate of 3 L/min. Both square and circle flow rates are
overlapped at the hole diameter of 0.5 mm.
[0029] The outline (condition) of the test is as follows. In the
test, in order to avoid adverse effects on the filling of gas
sampling bag 10 with gas or mixing of gas in the bag, temperature
difference and air stream were eliminated around the gas sampling
bag 10. The opening diameter of the pipe 19 and the inside diameter
of passages 11, 13 was commonly 6 mm. After filling the gas
sampling bag 10 with C.sub.3H.sub.8 at 50 ppm at flow rate of 6
L/min and 3 L/min for 100 seconds, the gas sampling bag 10 was also
filled with air for 400 seconds at the same flow rates (6 L/min and
3 L/min). After letting stand for 60 seconds, by applying impact to
the gas sampling bag 10, mixing of the inside C.sub.3H.sub.8 and
air was promoted, and the concentration of total hydrocarbon (THC)
was measured after the gas sampling bag was shocked by patting and,
on the basis of this reference value, the difference from the
concentration before impact was calculated in the following
formula, and the mixing error E (%) was determined.
E(%)=[(concentration after impact)-(concentration before
impact)]/(concentration after impact).times.100
[0030] As shown in FIG. 4, the mixing error is smaller in the hole
diameter of 1.5 mm as compared with 3.0 mm of the gas inlet/outlet
holes 21 opened in the pipe 19, and is further smaller in the hole
diameter of 0.5 mm. That is, as the opening diameter of the gas
inlet/outlet holes 21 becomes smaller, the mixing error is
improved, and the error margin becomes smaller. In particular, when
the opening diameter of the gas inlet/outlet holes 21 is 0.5 mm, at
the flow rate of 6 L/min in the general sampling condition, the
mixing error is reduced to 0.6%, that is, about 1/3 of the
conventional one, and even at a small flow rate of 3 L/min, the
mixing error is improved to 2%, that is, about 1/6 of the
conventional one. The velocity of the gas passing through the gas
inlet/outlet holes 21 can be increased to more than 30 times of the
conventional one.
[0031] Thus, in the general sampling condition at flow rate of 6
L/min, preferably, the mixing error should be 1% or less, and as
understood from FIG. 4, when the opening diameter of the gas
inlet/outlet holes 21 is 1.0 mm or less, the mixing error of each
case is 1% or less. Therefore, the opening diameter of gas
inlet/outlet holes 21 is 1.0 mm or less, more preferably 0.5
mm.
[0032] As described above, by narrowing the diameter of gas
inlet/outlet holes 21 formed in the pipe 19, the velocity of the
gas passing the gas inlet/outlet holes 21 is increased, and the gas
is sufficiently mixed and contained in the bag main body 18.
[0033] In the foregoing embodiment, when the opening diameter of
the pipe 19 is 6 mm, the opening diameter of the gas inlet/outlet
holes 21 is set at 0.5 mm, but not limited to this example, the
opening diameter of the pipe 19 and the opening diameter of the gas
inlet/outlet holes 21 may be set arbitrarily as far as the pressure
loss is suppressed so as not to increase as far as possible. The
number of gas inlet/outlet holes 21 formed in the pipe 19 is 52 in
the shown example, but the same effects are obtained by forming a
different number of holes.
[0034] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *